Question: A square piece of paper is folded in half to form a rectangle. If the resulting rectangle has a perimeter of 18 inches, what is the area of the original square, in square inches?
Solution: Let $s$ be the side length of the square. The rectangle has sides of length $s$ and $s/2$, and its perimeter is $3s = 18$. It follows that $s = 6$, so the area of the original square is $\boxed{36}$.